class Solution {
public:
    int tribonacci(int n)
    {
        if (n == 0 || n == 1) return n;
        if (n == 2) return 1;
        vector<int> dp(n + 1);
        dp[0] = 0;
        dp[1] = dp[2] = 1;

        for (int i = 3; i <= n; i++)
            dp[i] = dp[i - 1] + dp[i - 2] + dp[i - 3];
        return dp[n];
    }
};
class Solution {
public:
    int minCostClimbingStairs(vector<int>& cost)
    {
        int n = cost.size();
        vector<int> dp(n + 1);
        dp[0] = 0;
        dp[1] = 0;

        for (int i = 2; i <= n; i++)
            dp[i] = min(dp[i - 1] + cost[i - 1], dp[i - 2] + cost[i - 2]);
        return dp[n];
    }
};
class Solution {
public:
    int minCostClimbingStairs(vector<int>& cost)
    {
        int n = cost.size();
        vector<int> dp(n + 1);
        dp[0] = 0;
        dp[1] = 0;

        for (int i = 2; i <= n; i++)
            dp[i] = min(dp[i - 1] + cost[i - 1], dp[i - 2] + cost[i - 2]);
        return dp[n];
    }
};